▎ 摘　　要

A combination of reduced graphene oxide (rGO) nanosheets grafted with regioregular poly(3-hexylthiophene) (P3HT) (rGO-g-P3HT) and P3HT-b-polystyrene (PS) block copolymers was utilized to modify the morphology of P3HT:[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) active layers in photovoltaic devices. Efficiencies greater than 6% were acquired after a mild thermal annealing. To this end, the assembling of P3HT homopolymers and P3HT-b-PS block copolymers onto rGO-g-P3HT nanosheets was investigated, showing that the copolymers were assembled from the P3HT side onto the rGO-g-P3HT nanosheets. Assembling of P3HT-b-PS block copolymers onto the rGO-g-P3HT nanosheets developed the net hole and electron highways for charge transport, thereby in addition to photoluminescence quenching the charge mobility (mu(h) and mu(e)) values increased considerably. The best charge mobilities were acquired for the P3HT(50000):PC71BM:rGO-g-P3HT(50000):P3HT(7000)-b-PS1000 system (mu(h) = 1.9 x 10(-5) cm(2) V-1 s(-1) and mu(e) = 0.8 x 10(-4) cm(2) V-1 s(-1)). Thermal annealing conducted at 120 degrees C also further increased the hole and electron mobilities to 9.8 x 10(-4) and 2.7 x 10(-3) cm(2) V-1 s(-1), respectively. The thermal annealing acted as a driving force for better assembly of the P3HT-b-PS copolymers onto the rGO-g-P3HT nanosheets. This phenomenon improved the short circuit current density, fill factor, open circuit voltage and power conversion efficiency parameters from 11.13 mA cm(-2), 0.63 V, 62% and 4.35% to 12.98 mA cm(-2), 0.69 V, 68% and 6.09%, respectively. (c) 2019 Society of Chemical Industry